There are other cats in the house and he does wrestle with his sister so it's very possible there was a trauma to the eye. I can't see anything but I thought if I could rinse it with an eye rinse it might relieve the irritation. This just started tonight so I could also just wait until a.m.

Any sterile eyewash could be used to flush his eye in case there is debris in the eye causing the irritation. Just make sure there is no added medication in the wash. I would certainly take him in to see your regular vet as cats frequently get their cornea scratched or injured (essentially an eye ulcer) and results in squinting (due to pain) and discharge. Eye ulcers do require additional medications and can get worse very quickly, so quick diagnosis and treatment is important. A lot of times the scratch is not visible so a special stain (fluoroscein) can be used by your veterinarian to determine if there is an actual defect in the cornea.

These eye drops are benign but I don't think it will help in this situation because your cat's eye is unlikely dry (probably already tearing quite a bit). A flush would help (that you could squirt in the eye as a steady stream) if there were some debris in the eye. If you are unable to get a flush tonight, I would just get him in to your regular vet tomorrow morning if the squinting is still present. You could also look for an emergency clinic tonight if you would like to help relieve his discomfort sooner. It may be a little more costly but at least could be addressed tonight...